Per the hearing, the FBI is asking Apple to create a custom firmware that does not currently exist that:
*Removes the delay between password attempts
*Allows the ability to plug in a device that would send software password guesses rather than utilizing the hardware of the touchscreen
*Removes the 10 wrong guesses and it destroys the encryption key function
All three of which would qualify as a defect (number two especially, they want to be able to use the lightning port to hook up a device that sends passcode attempts, thousands per second. Imagine if that vulnerability got exploited, you'd have companies and criminals everywhere just making these devices as they did pre iOS 8).
But does it meet the definition of a "back door" as posted above or as used by Craig Federighi?
a feature or defect of a computer system that allows surreptitious unauthorized access to data.
The FBI's request of Apple is neither surreptitious nor unauthorized. Their request have been out in the open through legally provided and court-approved warrants coupled with probably cause.